Four preload methods for ball screws

The ball screw is a high-precision transmission element. The rolling screw is used instead of the sliding screw, and the sliding friction is converted into rolling friction. Therefore, it has the advantages of low wear, high transmission efficiency, stable transmission, long life, high precision, and high temperature rise.

The ball screw has low friction, which is convenient for eliminating transmission gaps and other outstanding advantages. It brings great benefits to the performance improvement of the motor integration system. However, the ball screw cannot be self-locking, and a locking device is required when used for lifting transmission.

Pre-tightening is to prevent the ball from slipping. The self-locking property of the ball screw is poor, or even non-existent, and it is easy to fall off without pre-tightening. However, not all ball screws are pre-tightened. It mainly depends on the accuracy requirements. Generally, the pre-tightening has high accuracy and large load capacity. There are four commonly used pre-tightening methods for ball screws. Let's take a look!

1. Double nut gasket pre-tightening, add a gasket between the double nuts, and the manufacturer can adjust the pre-tightening force in advance according to the user's request. It is very convenient to use and load and unload.

2. Double nut threaded pretightening uses the external thread on one nut to adjust the relative axial position of the two nuts through the round nut to achieve pretightening.

3. Double nut tooth difference pretightening, gears with a tooth number difference of 1 are cut out on the flanges of the two nuts respectively, and the two gears are meshed with the corresponding inner gear rings at both ends, and the inner gear rings are fastened to the nut seat with screws. By rotating and changing one of the nuts, the relative position of the two nuts is changed to adjust the gap and apply pretightening force.

4. Single nut variable lead self-pretightening, the internal thread raceway of the nut produces a lead mutation on the middle circle, so that the balls on the left and right ends are axially dislocated after installation to achieve pretightening.

In general, the nut gasket pretightening method is simple and reliable, has good rigidity, is the most widely used, and is also more popular.